Random-field Ising-type transition of pure and doped SBN from the relaxor into the ferroelectric state

Activated critical dynamics and vanishing of the susceptibility ratio alpha (3)=chi (3)/chi (4)(1)-->0 in the zero-frequency limit unequivocally evide nce the phase transitions of the uniaxial relaxor crystals SBN, SBN: Ce and SBN: Cr to refer to the three-dimensional random-field Ising universality class. The relaxor-like freezing of polar nanoregions within the precursor regime is successfully described within the framework of the mesoscopic uni axial spherical random-bond random-field model.